Nakanishi Kazuki, Lugo-Fuentes Leonardo I, Manabe Jun, Guo Ronghao, Kikkawa Soichi, Yamazoe Seiji, Komaguchi Kenji, Kume Shoko, Szczepanik Dariusz W, Solà Miquel, Jimenez-Halla J Oscar C, Nishihara Sadafumi, Kubo Kazuyuki, Nakamoto Masaaki, Yamamoto Yohsuke, Mizuta Tsutomu, Shang Rong
Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan.
Department of Chemistry, Division of Natural and Exact Sciences, University of Guanajuato, Campus Gto, Noria Alta s/n, 36050, Guanajuato, Mexico.
Chemistry. 2023 Nov 13;29(63):e202302303. doi: 10.1002/chem.202302303. Epub 2023 Oct 2.
Synthetic strategies to access high-valent iridium complexes usually require use of π donating ligands bearing electronegative atoms (e. g. amide or oxide) or σ donating electropositive atoms (e. g. boryl or hydride). Besides the η -(methyl)cyclopentadienyl derivatives, high-valent η carbon-ligated iridium complexes are challenging to synthesize. To meet this challenge, this work reports the oxidation behavior of an all-carbon-ligated anionic bis(CCC-pincer) Ir complex. Being both σ and π donating, the diaryl dipyrido-annulated N-heterocyclic carbene (dpa-NHC) Ir complex allowed a stepwise 4e oxidation sequence. The first 2e oxidation led to an oxidative coupling of two adjacent aryl groups, resulting in formation of a cationic chiral Ir complex bearing a CCCC-tetradentate ligand. A further 2e oxidation allowed isolation of a high-valent tricationic complex with a triplet ground state. These results close a synthetic gap for carbon-ligated iridium complexes and demonstrate the electronic tuning potential of organic π ligands for unusual electronic properties.
